1. Field of the Invention
The present invention relates generally to an apparatus for inspecting packaged electronic devices. More particularly, the invention is concerned with an apparatus for inspecting a printed circuit board (hereinafter referred to as a substrate) mounted or packaged with electric and/or electronic parts (hereinafter referred to as the packaged substrate or device), which apparatus is capable of automatically identifying discriminatively the types or species of electronic parts mounted on a substrate and examining the packaged device as to whether the parts thereof are mounted at respective correct positions on the substrate.
2. Description of the Prior Art
As the packaged device inspecting apparatus (also known as the package inspecting system) for inspecting the packaged electronic/electric device equipped with electric and/or electronic parts by using a mounter or the like means, there has heretofore been known such a structure as schematically shown in FIG. 1 of the accompanying drawings.
As will be seen in this figure, the packaged device inspecting apparatus or system is composed of a television camera (referred to simply as TV camera) 3 for picking up an image (also referred to as imaging) of a substrate 2b on which electronic/electric parts 1b are mounted or packaged and which is to be inspected and a reference packaged substrate 2a having parts 1a which serves as a reference or standard substrate for the inspection, a feature data extraction/storage unit 4 for extracting and storing the feature data of shapes, positions, colors of the parts 1a from the image (reference image) of the reference packaged substrate 2a picked up by the TV camera 3, circuit 5 for comparing the data of image (image to be examined) of the packaged substrate 2b under inspection available from the TV camera 3 with the reference image data stored in the feature data extraction storage unit 4 for making decision as to whether all requisite parts 1b are mounted on the packaged substrate 2b under test or whether any of the mounted parts 1b are displaced or dislocated from the respective correct positions, and a monitor unit 6 for displaying or printing out the results of the decision made by the comparison/decision unit 5.
In the packaged substrate inspecting apparatus known heretofore, the data resulting from the examination or inspection of the packaged substrate 2b under test are displayed or printed out by the monitor to thereby inform the inspector in charge of any package failure for the repair. In this connection, it is however noted that since the package failure information is displayed or printed out in terms of part identification numbers (serial numbers and/or part classification numbers, not only difficulty is encountered but also a lot of time is required for inspecting and repairing the faulty parts or portions by referring to the outputted part identification number in case several hundreds of parts are mounted on the substrate of concern, not speak of a lot of time and troublesome procedure.
On the other hand, it is difficult to store the positions of the parts mounted on the substrate in combination with the respective assigned identification numbers. In reality, a lengthy troublesome procedure will be required for satisfactory of erroneous memorization, lapse of memory and degradation in reliability.
Further, in the case of the hitherto known packaged device inspecting apparatus, the standard image and that of a packaged substrate under test obtained through the TV camera 3, being followed by extraction of the data concerning the positions and the shapes of the parts 1a and 1b, wherein inspection is made as to whether the part 1b is correctly mounted by comparing the positions and shapes with those of the reference part 1a. Accordingly, in case parts incorporated in the reference packaged device and the device under test are of a same color as that of the blank substrate material of the packaged devices, the threshold level for digitizing the reference image signal and that of the device under test can not be definitely determined, making it impossible to extract the feature data of the parts 1a and 1b.
Besides, in the case of the conventional packaged device inspecting system, the package to be examined is inspected one by one for deciding if the device of concern is satisfactory, wherein the result of the decision is displayed to give information to the operator on the one-by-one basis whether the device now examined is good or not. Consequently, even when only a specific part becomes faulty due to failure in a corresponding mounter upon manufacturing of the individual packaged substrate 2b under test, it is impossible to detect the failure of the specific part at an earlier stage for eliminating the cause for the failure, giving rise to a problem.
The prior art packaged substrate inspecting apparatus of the type outlined above is so designed as to compare directly the image of the part 1a mounted on the standard or reference packaged substrate 2a with that of the part 1b mounted on the printed substrate 2b under inspection for detecting the absence or positional deviation of the part 1b. Accordingly, even when the positions and sizes of land patterns formed on the substrate are not matched with the sizes and shapes of the parts 1a and 1b due to error in design, resulting in that the part 1b and the corresponding land pattern are not in the predetermined positional relationship, there arises a possibility that the decision is made to the effect that the part 1b is mounted satisfactorily.